LU-11546 utils: enable large_dir for ldiskfs

LU-11546 utils: enable large_dir for ldiskfs

Format MDT with "large_dir" option by default,
to get over the 10M-entry limit for the directories.

Lustre-change: https://review.whamcloud.com/36555
Lustre-commit: cd1faa0124f21e12a5ecd83c709c13918264fc86

Signed-off-by: Li Dongyang <dongyangli@ddn.com>
Change-Id: Ie51e6ce28b5f00adc9958de24794a760d9b43b77
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Artem Blagodarenko <c17828@cray.com>
Reviewed-by: Stephan Thiell <sthiell@stanford.edu>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/36781
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Artem Blagodarenko <artem.blagodarenko@hpe.com>
Tested-by: Maloo <maloo@whamcloud.com>